This document discusses issues with relying on sense perception as a way of knowing. It provides examples of how we may fail to see something that is there or see something that is not there. Images shown may lead us to see what we expect rather than what is actually there. Moving images and sounds can also be problematic in similar ways. Our perceptions are subject to the limitations of our sensory systems and psychological effects, so what we experience may not accurately represent the external world. In summary, sense perception has limitations and is not always a reliable way of knowing.

1. Sense Perception
Some examples
&
some questions…

2. Study the picture which will appear below.
What do you notice? (Don‟t tell everyone!)

4. Look at the toast carefully…..what do you see?

5. • Already we have two issues to bear in
mind when assessing sense
perception as a way of knowing
• We may fail to see something that is
there
• We may see something that is
(possibly) not there

6. More problems…
• Think about why the following
images are problematic

7. PARIS
IN THE
THE SPRING
Did you see what was there, or what
you expected to see?

8. Do you “perceive” what you see?

9. Do you “see” what you perceive?

12. Moving pictures can also be
problematic…
• http://www.youtube.com/watch?v=sKa0eaKsdA0
http://www.youtube.com/watch?v=jP_jYmbke14
• http://www.michaelbach.de/ot/mot_adapt/index.html

13. Concentrate on the cross in the middle, after a while you will notice that this
moving purple dot will turn green!
What happens after you„ve
looked at the cross a bit
longer ?

14. On the other hand, motion may
clarify what we see
• picture 1
• picture 2

15. What causes these problems?
• Context may mislead us
• There may be different, but equally valid
interpretations of what we see
• We may see something only when
someone else tells us it is there
• We jump to conclusions, seeing what
we expect to see
• We impose order on what we see

16. Are there similar problems with
our other senses?
• taste
• smell
• touch
• hearing
• any other senses

17. Some sound problems
• http://asa.aip.org/demo27.html
• http://jeffmilner.com/backmasking.htm

18. There is some reading for you to take away
about sense perception for bats.

19. Conclusions?
• The sensations we experience are subject to the
limitations of the body‟s sensory systems and may not
therefore be a true representation of the external world
Examples could include
• frequency limitations for hearing which vary with species
or individual
• sight limitations such as colour-blindness or lack of focus
• psychological effects may cause sensations without an
external cause.
• temporary confusion may be induced by conflicting
messages
or
• we may overinterpret what we sense!

20. We could say…
Our internal constructions may
differ from the external world
or
“The eye is not a camera”